<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            width: 200px;
            height: 200px;
            background-color: pink;
            position: relative;
        }

        span {
            position: absolute;

            width: 10px;
            height: 10px;
            transform: rotate(45deg);
            bottom: -5px;
            right: 106px;
            z-index: 199;
            opacity: 0;
            background-color: #f4f4f4;
        }
        .box:hover span{
            opacity: 1;
        }
    </style>
</head>

<body>
    <div class="box">
        <span></span>
    </div>
</body>

</html>